Transmembrane movement of a substance with a concentration gradient, with no involvement of membrane proteins, is called ________.
Fill in the blank(s) with the appropriate word(s).
diffusion
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Alternate forms of a gene are best described as _____
A. homologues B. loci C. alleles D. homozygous E. heterozygous
What scientist(s) first demonstrated in the laboratory that organic compounds could be synthesized in an abiotic environment?
a) Rosalind Franklin b) Haldane and Oparin c) Urey and Miller d) Watson and Crick e) Anton Van Lueenhoech
The ideal Christmas tree has a conical shape. The top of the tree is pointed and narrow, with clear apical dominance, and the bottom of the tree is wide, with extensive lateral branching
Certain evergreen species are suitable for use as Christmas trees because they have this shape normally and thus require little pruning or training as they grow. For example, spruces and firs are often grown as Christmas trees, whereas yews and longleaf pines are not. Based on this information, spruces and firs are likely to have A) high levels of auxins near the top and low levels of cytokinins at the bottom of the tree. B) high levels of auxins near the top and high levels of cytokinins at the bottom of the tree. C) low levels of auxins near the top and high levels of cytokinins at the bottom of the tree. D) low levels of auxins near the top and low levels of cytokinins at the bottom of the tree.
Endotoxins are
A) associated with gram-positive bacteria. B) molecules that bind nerve cells. C) part of the gram-negative cell wall. D) excreted from the cell. E) A-B toxins.